When a user grabs an object, forces are exerted on a user's body by which the object is touched. That is, the forces are exerted on points of contact in the user's body. For example, when the user grabs the object, the forces work between the object and the user's hand. As the forces are delivered to fingers, the user may feel physical properties of the object. Herein, a force may be generated in a direction normal to a contact surface.
Even though the user actually does not grab the object, if the forces are applied to the user's body from the outside, the user may feel sensation as if the user grabbed the object. In other words, an apparatus for applying the forces to the user's body from the outside may enable the user to feel the sensation as if the user grabbed the object. Such apparatus for enabling the user to feel a virtual sensation may be widely used in a system for implementing a virtual world, etc. Haptic devices have been developed as tools for applying forces to users in the virtual world.
However, most of existing haptic devices apply forces to ends of the body of a user (e.g., fingertips as points of contact). Such existing haptic devices have problems as follows: the volume of the devices is increased and a pose of a hand or a finger becomes unnatural or limited.
Therefore, the present inventor came to develop a technology for applying torques to user's joints instead of applying forces to ends of the user's body by which an object is touched and relatively supporting the user's flexible motion.